Five gunshot victims are in critical condition but are expected to survive. At least a dozen people who escaped gunshot wounds were treated for smoke inhalation and other injuries.

Here is a look at how the attack and the subsequent investigation is unfolding.

What happened?

An everyday morning commute turned into a scene of horror Tuesday with witnesses describing a smoke-filled underground car, an onslaught of at least 33 bullets, screaming riders running through a station, and bloodied people lying on the platform as others tended to them.

A riders’ videos show a person in a hooded sweatshirt raising an arm and pointing at something as five bangs sound.

Sitting in the back of the train’s second car, the gunman tossed two smoke grenades on the floor, pulled out a Glock 9 mm semi-automatic handgun and started firing, Chief of Detectives James Essig told The Associated Press. He said the police found the weapon, along with extended magazines, a hatchet, detonated and undetonated smoke grenades, a black garbage can, a rolling cart, gasoline and the key to a U-Haul van.

At least 23 were injured, five critically, in an attack at the 36th Street subway stop in Sunset Park after a man released two smoke grenades and started shooting. — 5.7 x 7.0 — cat=a

Investigators believe the shooter’s gun jammed, preventing him from continuing to fire, as per initial reports.

The investigation

The police said the gunman is believed to have acted alone and immediately fled the crime scene. The subway assailant was described by the police from eyewitness accounts as a man of heavy build, wearing an orange vest, a gray sweatshirt, a green helmet and surgical mask.

Meanwhile, the New York Police Department has identified Frank James as a suspect in the Brooklyn subway shooting. The key retrieved from the site of the attack led investigators to James, a 62-year-old man who has addresses in Philadelphia and Wisconsin, the detective chief told AP. The van was later found, unoccupied, near a subway station where investigators determined the gunman entered the train system, Essig said.

Frank James is shown in this handout photo provided by the New York City Police Department, April 12, 2022. (New York City Police Department (NYPD)/Handout via Reuters)

Authorities were looking at his apparent social media posts, some of which led officials to tighten New York Mayor Eric Adams’ security detail. Police Commissioner Keechant Sewell called the posts “concerning.”

Why are James’ posts ‘concerning’?

Rambling, profanity-filled YouTube videos apparently posted by James are replete with Black nationalist rhetoric, violent language and bigoted comments, some of them directed at other Black people, reported AP.

One, posted April 11, criticises crime against Black people and says drastic action is needed to change things. Another, from March 20, says the nation was “born in violence, it’s kept alive by violence or the threat thereof and it’s going to die a violent death.”

A February 20 video says the mayor and governor’s plan to improve safety in New York City’s subway system “is doomed for failure” and refers to himself as a “victim” of the mayor’s mental health program. A January 25 video — called ‘Dear Mr Mayor’ — is somewhat critical of Adams’ plan to end gun violence.

What about CCTV footage?

The Metropolitan Transportation Authority which is responsible for transportation in the New York City area announced last year that it had installed security cameras in all 472 subway stations citywide. But cameras weren’t working at three stations where police went to look for evidence Tuesday, Essig said.

Emergency personnel work at the scene of a shooting at a subway station in the Brooklyn borough of New York City, New York, US, April 12, 2022. (Reuters)

MTA system chief Janno Lieber told TV interviewers he didn’t know why the cameras malfunctioned, said an AP report.

As police searched for the shooter, Gov. Kathy Hochul warned New Yorkers to be vigilant. “This individual is still on the loose. This person is dangerous,” Hochul said.